souveran != P21S but very close!
P21S = S100 and s100 is much cheaper.
The best bang for your buck on apperance is S100. Durability will be collinite. I have actually gone as far as using megs #7 glaze (always go around the car 2x on the removal step as it never truly dries) then topped that with S100, followed by some collinite for durability and one more coat of S100 for the sheer beauty of it.